MX2014008989A - Folding unit for pourable food product packaging machines. - Google Patents

Abstract

There is described a folding unit (1) for producing packages (2) of pourable food products from sealed packs (3) having each a main portion (7) and opposite end portions (8, 9) arranged on opposite sides of main portion (7); each pack (3) comprising, for each end portion (8, 9), a fin (17, 18) and a pair of flaps (19, 20) projecting laterally from main portion (7); unit (1) comprises: a conveyor (60) which is fed with a plurality of packs (3) and which feeds the pack (3) along a forming path (B); and folding means (24) which interact with each pack (3) along forming path (B) to fold relative end fin (18) onto a relative end portion (8); conveyor (60) comprises at least a first and a second link (35a, 35b) articulated to each other; second link (35b) is arranged downstream of first link (35a), with reference to a first advancing direction of conveyor (60)along forming path (B); folding means (24) comprise: a slot (40) which is defined by first link (35a) and is adapted to receive said end fin (18); and a slide (72) operatively connected to second link (35b) and movable between a first position in which it at least partially engage slot (40), so as to fold said end fin (18) onto a relative said end portion (9), and a second position in which it is detached from slot (40).

Description

BENDING UNIT FOR PRODUCT PACKAGING MACHINES FOOD SAFETY Field of the Invention The present invention relates to a folding unit for producing folded packages of pourable food products from relative sealed packages.

Background of the Invention As is known, many food products, such as fruit juice, pasteurized milk or UHT (treated at ultra-high-temperature) milk, wine, tomato sauce, etc., are sold in packages made of sterilized packaging material.

A typical example of this type of packaging is the parallelepiped packing for liquid or pourable food products known as Tetra Brik Aseptic (registered trademark), which is made by folding and sealing laminated band packaging material.

The packaging material has a multilayer structure substantially comprising a base layer for stiffness and strength, which may comprise a layer of fibrous material, eg paper, or mineral-filled polypropylene material; and a number of layers of heat sealing plastic material, eg, polyethylene film, covering both sides of the base layer.

Ref. 249386 In the case of aseptic packaging for prolonged storage products, such as UHT milk, the packaging material may also comprise a layer of material with gas and light barrier, for example an aluminum foil or a sheet of ethyl vinyl alcohol ( EVOH), which is superimposed on a layer of heat sealing plastic material, and this in turn covered with another layer of heat sealing plastic material that forms the inside face of the package eventually in contact with the food product.

As is known, packages of this kind are produced in fully automatic packaging machines, in which a continuous tube is formed from the packaging material fed into the membrane. The membrane of packaging material is sterilized in the packaging machine, for example, by applying a chemical sterilizing agent, such as a hydrogen peroxide solution, which, once the sterilization is complete, is removed from the surfaces of the material of packaging, for example evaporated by heating. The membrane of packaging material thus sterilized is maintained in a closed, sterile environment, and is folded and longitudinally sealed to form a vertical tube.

The tube is continuously filled down with sterile or sterilized processed food product, and is sealed and then cut along sections transversely equally spaced to form pillow-like packages, which can be fed to a folding unit to form the finished packages.

More specifically, the pillow-type packages substantially comprise a main portion, and opposite upper and lower end portions that taper from the main portions toward the respective upper and lower seal bands extending substantially orthogonal to the axis of the package. In detail, each end portion is defined by a pair of respective trapezoidal walls extending between the main portion of the package and the relative sealing band.

Each pillow-type package also comprises, for each upper and lower end portion, an elongate, substantially rectangular fin formed by the respective sealing band; and a pair of substantially triangular flaps projecting from opposite sides of the relative end portion and defined by the end portions of the respective trapezoidal walls and by the corresponding triangular portions protruding from the main portion.

The end portions are pressed towards each other by the bending unit to form flat opposite end walls of the package, while at the same time bending the flaps of the upper part over the respective ones. side walls of the main portion and the flaps of the lower portion on the lower sealing band.

Packaging machines for producing packages of the above type are known, typically comprising: - an infeed conveyor; - a bending unit that receives the pillow-type packages from the input infeed conveyor and adapted to fold these pillow-type packages to form the parallelepiped-shaped packages; - a transfer unit for transferring and finishing sealed folded packages, which is disposed downstream of the folding unit and receives the sealed packages from the folding unit; Y - an output feed conveyor that receives bent packages from the transfer unit and moves them away from the packaging machine.

Folding units are known, for example, from EP-A-0887261 in the name of the same applicant, which substantially comprise: - a chain conveyor for feeding packages continuously along a formation path from a supply station to an output station; Y - first bending means and second bending means, cooperating cyclically with each package to flatten the respective end portions of each package and thus fold the respective fins on the end portions.

In detail, the first bending means comprises a fixed guide member, which is located in front of and at a distance from a chain transport portion, and converges towards this transport portion. The fixed guide member cooperates with the lower end portion of each package to press it horizontally towards the chain.

The second bending means comprises a pair of contrast elements defined by parallel elongated sections mounted in a fixed frame adjacent to the respective opposite lateral edges of the conveyor chain. More precisely, the contrast elements cooperate in sliding manner with the upper end portion of each package to bend the upper fin towards the main portion of the relative pack, and upper flaps on this main portion.

In this way, since the chain conveyor feeds the packages in a first direction, the relative upper flaps are bent over the main portion flattened in a second direction, opposite the first direction.

In detail, the upper flaps are folded over the flattened main portion on the opposite side of a longitudinal sealing band.

Although effective, packaging machines of the above type leave room for improvement.

In particular, the need is felt within the industry to make controllable as possible the bending of the upper fins on the flattened main portion of the corresponding packages.

In particular, the need is felt within the industry to bend the upper fin as coplanar as possible over the flattened main portion.

Brief Description of the Invention It is an object of the present invention to provide a bending unit for a pourable food product machine, designed to provide a simple and inexpensive solution for satisfying at least one of the above needs, typically associated with the known bending unit.

According to the present invention, there is provided a folding unit for producing folded packages of pourable food products from relative sealing packages, according to claim 1.

Brief Description of the Figures Figure 1 shows a side view, with parts removed for clarity, of a folding unit according to the present invention for producing folded packages of pourable food products from the sealed pillow packs; Figure 2 is an enlarged side view of the unit of folding of Figure 1, with parts removed for clarity; Figure 3 is an enlarged view of some components of the unit of Figure 2, with parts removed for clarity; Figures 4 to 17 show some components of the unit of Figures 1 to 3, with parts removed for clarity; Y Figure 18 shows an enlarged perspective view of a package of the folding unit of Figures 1 to 17.

Detailed description of the invention Number 1 in Figure 1 indicates as a whole a bending unit for a packaging machine (not shown) for continuously producing sealed packages 2 of a pourable food product, such as pasteurized milk or UHT, fruit juice, wine, etc. ., from a known tube of packaging material (not shown).

The tube is formed in a known manner upstream of the unit 1 by longitudinally folding and sealing a known membrane (not shown) of thermal sealing sheet material which may comprise a base layer for rigidity and strength, which may be formed by a layer of fibrous material, for example, paper, or of mineral-filled polypropylene material, and a number of layers of thermally sealed plastic material, for example film of polyethylene, covering both sides of the base layer. In the case of an aseptic package 2 for prolonged storage products, such as UHT milk, the packaging material may also comprise a gas layer and light barrier material, for example an aluminum foil or a sheet of ethyl vinyl alcohol (EVOH), which is superimposed on a layer of heat sealing plastic material, and is in turn covered with another layer of heat sealing plastic material forming the inside face of the gasket 2, possibly in contact with the food product.

The tube of packing material is then filled with the food product, and sealed and cut along equally spaced cross sections to form a number of pillow-like packages 3 (Figure 18), which is then transferred to unit 1 , where they are bent mechanically to form respective parallelepiped shaped packages 2.

Alternatively, the packaging material can be cut into punched pieces, which are formed in the packages 2 with shaping spindles, and the packages 2 are filled with the food product and sealed. An example of this type of packaging is the so-called "gabled" package known by the trade name Tetra Rex (registered trademark).

In detail, unit 1 receives pillow type packages 3 of a feed conveyor 41 and feed the folded pack 2 to the feed conveyor 42 (Figure 1).

With reference to Figure 18, there is shown an embodiment of a package 3 having a longitudinal sealing band 4, formed to produce the tube of packing material of the band bent in a cylinder, extends along one side of the other. each package 3, which is closed at opposite ends by respective transverse sealing strips 5, 6 perpendicular and joined to the longitudinal sealing strip 4.

Each package 3 has an axis A, and comprises a main body 7 and opposite, respectively upper and lower end portions 8, 9 tapered from the main body 7 towards the respective transverse sealing bands 5, 6.

The main body 7 of each package 3 is laterally limited by two side walls 10a and two side walls 10b, which are alternate with each other.

Each end portion 8, 9 is defined by two walls 12, each substantially in the shape of an isosceles trapezium, which slopes slightly towards each other with respect to a plane perpendicular to axis A, and have minor edges defined by end edges respective top and bottom of the respective wall 10a, and major edges joined together by respective sealing bands 5, 6 The longitudinal sealing band 4 extends between the transverse sealing strips 5 and 6, and along the entirety of a wall 10a and the corresponding walls 12 on the same side as the wall 10a.

Each pack 3 also comprises, for each end portion 8, 9, a respective substantially elongated rectangular end flap 17, 18 formed by respective sealing strips 5, 6 and protrudes in the direction of the axis A of the respective pack 3; and two substantially triangular flaps 19, 20 projecting laterally on opposite sides of the main body 7, and defined by end portions of the relative walls 12 and corresponding corresponding triangular end portions of the side walls 10b.

More precisely, each end flap 17, 18 extends along a direction orthogonal to axis A.

To form a package 2, the unit 1 presses the end portions 8, 9 of the relative pack 3 horizontally towards one another and at the same time bends the respective fins 17, 18 into flattened end portions 8, 9. In particular, the fin 18 is bent over the end portion 9 on the opposite side of the sealing band 4.

In addition, the unit 1 bends the flaps 20 over the upper ends of the respective walls 10b towards the end portion 8 and fold the flaps 19 over the previously bent fin 17, on the opposite side of the end portion 9.

With reference to Figures 1, 2, 8 and 9, unit 1 substantially comprises: - a frame 29; - an endless conveyor 34 for feeding the packages 3 continuously along a formation path B from a supply station 21 to an output station 22 (both shown only schematically); - the bending means 23 cooperating cyclically with each pack 3 to flatten the end portion 8, bend the relative fin 17 over the end portion 8, and fold the fins 19 onto the previously flattened end portion 8 on the opposite side of the end portion 9; - the folding means 24 for bending the relative fin 18 on the flattened portion 9; - the bending means 37 for flexing the flaps 20 towards the axis A and end portion 8; - a heating device 27 acting on the flexed flaps 19, 20 to melt the outer layer of the packing material of the flaps 19, 20 before they are pressed and sealed against the end portion 8 and the relative walls 10b, respectively; Y - a pressure device 28 cooperating with each package 3 to maintain the flaps 19 on the flattened flap 17 while the flaps 19 are cooled.

As the packages 3 advance along the path B, the wall 10a with the longitudinal sealing strip 4 is disposed downstream of the wall 10a without longitudinal sealing strip 4.

The heating device 27 is, in particular, arranged between the bending means 23 and the pressure device 28 along the formation path B.

With particular reference to Figures 2, 4, 5 and 6, the conveyor 34 basically comprises an endless transport element, in the example a chain 60 is shown, formed by a plurality of rigid mutually articulated modules or links 35 and serpentine around of a pair of coaxial drive gears 26 and a cam 25.

The chain 60 comprises an upper horizontal straight division 30, a lower division 31 substantially parallel to the division 30, and two curved C-shaped portions 32, 33, which are positioned with their concavities oriented towards one another and connect the divisions 30 and 31; more specifically, the C-shaped portion 32 cooperates with the drive sprockets 26, while the C-shaped portion 33 cooperates with the cam 25.

Each link 35 comprises a substantially flat plate 36 adapted to receive a relative package 3, and a blade 43, projecting perpendicularly from the plate 36 on the opposite side of the drive sprockets 26 and the cam 25 and cooperating with and pushing a corresponding wall 10a of a package 3 relative to feed it along path B.

In particular, the blade 43 of each link 35 cooperates with the wall 10a without longitudinal sealing band 4.

The cam 25 is described in more detail in the European Application "Folding unit for producing folded packages of pourable food products from relative sealed packs", filed by the applicant with the application number EP11187351.9.

Unit 1 comprises (Figures 5 and 9 to 14) a plurality of housing pairs 50 that are integrally mobile along path B and are movable along a direction C transverse to path B; the 50 casings of each pair can be arranged in: - a completely closed position in which they exert a pressure on a relative package 3, in order to complete a folding operation therein; Y - an open position in which they are separated from the folded packing 2.

In addition, the housings 50 can also be arranged in a closed position, in which they grip the folded packing 2 but substantially does not exert any pressure on it.

In detail, station 21 is defined by the C-shaped portion 32 and station 22 is defined by lower division 31 at a position closer to the C-shaped portion 32 than to the C-shaped portion 33.

Path B comprises (Figure 2), starting from station 21 to station 22: a portion P from station 21, comprising a curved section IP and a straight section P2, along which the packages 3 are folded into relative packages 2; a curved portion Q along which the packages 2 are overturned 180 degrees; Y - a straight portion R disposed downstream of the curved portion Q and upstream of the station 22.

In detail, the section Pl is defined by a part of the C-shaped portion 32 and the section P2 is defined by the upper arm 30 of the chain 60. The portion Q is defined by the C-shaped portion 33, and the portion R is defined by the lower division 31 of the chain 60.

The bending means 23 cooperates cyclically with each package 3 along the portion P.

The folding means 24 are defined by the links 35 and, therefore, move together with the chain 60 as along path B.

In detail, the folding means 24 of the flattened end portion 9, bends the relative fin 18 over the portion 9 and the flexed flaps 20 towards the axis A and the end portion 8, since the relative pack 2 is brought to along section Pl of portion P (Figures 8 and 9).

The heating device 27 acts on the bent flaps 19, 20 to melt the outer layer of the packing material of the flaps 19, 20 before they are pressed and sealed against the end portion 8 and the upper ends of the relative walls 10b , respectively, since the package 2 is carried along the section P2 of the portion P (Figure 9).

In detail, the shells 50 of each pair move cyclically according to the next work cycle.

The housings 50 of each pair are arranged in the open position in the station 21, move from the open position to the fully closed position along the section Pl and an initial part of the section P2, and arrive at the fully closed position a along a remaining part of the P2 section. In the embodiment shown, the housings 50 reach the fully closed position downstream of the heating device 27 and upstream of the pressing device 28, proceeding in accordance with the direction of advance of the chain 60.

When the housings 50 are arranged in the fully closed position, they exert a certain pressure on the relative walls 10b adjacent thereto.

More precisely, while moving between the open position and the fully closed position along the section P2 of the portion P, the casings 50 of each link 35 perform two functions: - first, they complete the flexing of the flaps 20 of the relative walls 10b; Y then, they press the flaps 20, which have been previously flexed and heated, on the upper ends of the relative walls 10b.

In addition, the shells 50 of each pair move from the fully closed position to the closed position at the beginning of the Q portion.

Along the portion Q, the housings 50 move integrally parallel to the direction C and relative to the respective blade 43 (Figure 6).

In the embodiment shown, the housings 50 move away from one another for a distance, for example, 2-4 mm, when moving from the fully closed to the closed position.

In the remainder of the present description, only one link 35 will be described in detail, it being clear that all the links 35 are identical to each other.

The link 35 comprises (Figures 10 to 14): - plate 6; - the blade 43; - A pair of housings 50 that can move with respect to the blade 43 along the direction C; A pair of arms 51 connected to the relative housings 50, elongated parallel to the direction C and each comprising a relative slider 53; Y - a pair of guides 54 extending on opposite sides of the relative blade 43 along the direction C, and with respect to which the sliders 53 move parallel to the direction C.

Referring again to Figures 1 and 2, the plate 36 is disposed below, and then supports, the pack 3 (or pack 2) along the portion P and a starting portion of the portion Q of the path of training B.

On the other hand, the plate 36 is disposed above the package 2 along the portion R of the formation trajectory B. Consequently, the folded package 2 is released, under the action of gravity in the station 22, at conveyor 42.

The housings 50 define, on their sides opposite the arm 51, the relative surfaces 52 which are adapted to cooperate with the package 3 and which one faces the other .

The surfaces 52 are flat, in order to control the final shape of the gaskets 2.

Each arm 51 comprises, at its end opposite the relative housing 50, a roller 55.

Each slide 53 is disposed between the relative housing 50 and the roller 55 of the relative arm 51. Furthermore, each slide 53 can slide parallel to the direction C in relation to the guide 54.

In the embodiment shown, each arm 51 is integral with the relative housing 50.

The blades 43 are flat.

Advantageously, the folding means 24 comprises, for each pair of consecutive links 35a, 35b to each other: - a slot 40 defined by the upstream link 35a and adapted to receive the end flap 18 of a relative gasket 2; - a slide 72 operatively connected to the downstream link 35b and movable between a first position (shown in Figures 2 and 3 with reference to the links 35 that travel along the section P2) into which the slot 40 engages; in order to bend the end flap 18 housed therein, and a second position (shown in Figures 2 and 3 with reference to the links 35 moving along the section Pl) in which it leaves free the 4O slot.

In particular, the expressions "upstream link 35a" and "downstream link 35b" indicate a pair of consecutive links 35 which are arranged respectively upstream and downstream with reference to the direction of advance of the chain 60 along the trajectory B (Figure 3).

Accordingly, it should be clear that each link 35 comprises, with reference to the forward direction of the chain 60 along the path P: - a slider 72 adapted to be coupled to the slot 40 of an additional upstream consecutive link 35; Y - a slot 40 adapted to be coupled by a slide 72 of a further downstream consecutive link 35.

In more detail, each link 35 comprises a slide 72 which is disposed upstream of the slot 40, proceeding according to the direction of link advance 35 along path B.

The plate 36 of each link 35a, 35b comprises (Figures 2 and 3): - an upstream portion 140 of which the relative blade 43 protrudes on the opposite side of the cam 25 and pinions 26; Y - a downstream portion 141 to which a body 142 is connected.

The body 142 defines the slot 40 together with the portion 140. In particular, the slot 40 extends orthogonal to the plane in which the path B is located.

In particular, the body 142 comprises (Figure 16): - a pair of plates 143 connected to the portion 140; Y - a C-shaped bridge 144 protruding from the plate 143 on the opposite side of plate 36.

The bridge 144 includes, in turn: - a pair of arms 145 tangential to path B and connected to relative plates 143; Y - an arm 146 orthogonal to path B and extending between arms 145.

The arms 145 and relative plates 143 define corresponding grooves 147 tangent to the trajectory B.

The slits 147 are open at the relative sides that are opposite the relative plates 143. In other words, the open sides of the slits 147 face one another.

In particular, the arm 146 supports the end portion 9 of the package 3 is bent while the fin 18 is housed with the space within the slot 40.

The arms 145 comprise, on the side opposite the plate 143, relative slots 148 which are open on the side opposite the plate 36.

The recesses 148 laterally delimit the slot 40 and are adapted to cooperate with respective opposite lateral ends of the vane 18.

The slider 72 comprises, from the portion 140 of the downstream link 35b to the upstream link 35a, (Figures 7 and 9 to 15),: a lever 160 hinged to the upstream portion 140 about an axis that is orthogonal to the plane of the path B; - a plate 162 located in a plane that is tangential to the path B and one end of which enters the slot 40, when the slide 72 reaches the first position; Y - a pair of bolts 161 projecting from the plate 162 on the opposite side of the lever 160 and sliding inside the relative grooves 147 of the body 142 connected to the immediately upstream link 35a.

In detail, the plate 162 protrudes from the plate 36 on the opposite side of the body 142.

The bending means 37 also comprises a pair of lifting elements 170 (figures 8 and 17) having respective ends 171 interacting with the flaps 20, as relative packages 3 move along the section P2 of the path B.

In detail, the elements 170 are shaped as cylinders.

The elements 170 are stationary with respect to the path B, and are, in the embodiment shown, mounted in the frame 29.

As shown in Figures 2 and 3, the slide 72 is disposed in the second position in the station 21, moves from the second to the first position along the curved section Pl of the path B, remains in the first position along the straight section P2 of the trajectory B, it moves from the first position to the second position along the curved portion Q of the trajectory B, and is maintained in the second position along the straight portion R from path B and from station 22 to station 21.

In detail, the movement of the slide 72 from the second position to the first position along the curved section Pl is due to the fact that the angular distances between the consecutive links 35a, 35b decreases, since these links 35a, 35b are they move along the curved section Pl in the forward direction of the chain 60.

More precisely, the flap 18 of the package 3 is disposed within the open slot 40 of the link 35 in the station 21 Due to the fact that the slide 72 is carried by the downstream link 35b, the slot 40 is made by the upstream link 35a and the sealing band longitudinal 4 is formed in the wall 10a which is disposed downstream proceeding according to the forward direction of the link 35 along the path B, the slide 72 bends the fin 18 over the end portion 9 towards the upstream link 35a . Therefore, the slide 72 bends the flap 18 on the opposite side of the longitudinal sealing strip 4.

In this step, the ends 171 lift the flaps 20 towards the end portion 8 and the flaps 20 flexed with respect to the axis A, until they reach the position shown in Figure 8.

In the same way, the movement of the slide 72 from the first position to the second position along the curved section Q is due to the fact that the angular distances between the consecutive links 35a, 35b increases, since these links 35a, 35b move along the curved section Q in the forward direction of the chain 60.

The corresponding housings 50, while moving from the open position to the fully closed position, press the flaps 20 against the upper ends of the relative walls 10b, downstream from the bending means 23 and the heating device 17, proceeding from according to the direction of advance of the chain 60.

Unit 1 also comprises a pair of cams 61 (Figures 4 and 5) adapted to control the movement of each pair of housings 50 between the relative fully closed position, the closed position and the open position, since each pair of housings 50 advances along path B.

In addition, the cams 61 also control the movement of each pair of housings 50 integrally with each other along the direction C and in relation to the corresponding link blade 43.

In detail, the cams 61 are disposed on opposite side sides of the chain 60.

A cam 61 comprises a slot 62 which is engaged by the rollers 55 of the first casings 50.

The other cam 61 comprises an additional slot 62 which is coupled by the rollers 55 of the second casings 50.

With reference to Figures 4 and 5, the slits 62 comprise, proceeding from station 21 to station 22,: - relative straight portions 63 which are adapted to maintain the shells 50 of each pair in the open position; - relative converging portions 64 which are adapted to move housings 50 from the open position with respect to the totally closed portion relative to the section P2 of the portion P; - relative straight portions 65 that are adapted to hold shells 50 of each pair in the fully position respective closed; - relative curved portions 66 which are adapted to move the housings 50 from the respective fully closed position to the respective closed position; the relative curved portions 66 are also adapted to move the housings 50 integrally with respect to the blade 43 and in parallel to the respective directions C; Y - relative curved portions 67 which are adapted to move the housings 50 from the respective closed position to the respective open position.

Folding means 23 comprises a guide member 45 mounted in a fixed position between the station 21 and the heating device 27 (Figure 1).

The guide member 45 defines a contrast surface 46 that converges towards the chain 60 and cooperates in a sliding manner with the end portion 8 of each package 3 to compress and flatten the end portion 8 towards the chain 60.

The frame 29 also comprises a pair of fixed sides 68 (only one is shown in Figure 1) to laterally contain the packages 3 along the path B, located on opposite sides of the chain 60, and extending between the station 21 and the heating device 27.

The heating device 27 comprises (Figures 1, 8 and 9): - an air device 69 mounted on the frame 29; a pair of first nozzles 70 connected to the device 69 and adapted to direct hot air over the flaps 20 of each package 3 before each package 3 reaches the final pressing device 28; Y - a pair of second nozzles 71 connected to the device 69 and adapted to direct the hot air over the flaps 19 of each package 3 before a relative pair of casings 50 reaches the closed position completely.

The pressure device 28 comprises (Figure 1) a belt 80 wound on a drive wheel 81 and a drive wheel 82. The belt 80 comprises, on its outer surface opposite the wheels 81, 82, a plurality of projections 83 which they are adapted to press the flaps 19 of each package 3 on the respective flap 17.

The volume of each package 2 in the formation is controlled, downstream of the heating device 27, inside a compartment delimited by: - relative link blades 43 and link 35 immediately downstream proceeding according to the direction of advance of chain 60; - relative link casings 50 which are arranged in the fully closed position; - relative link plate 72 arranged in the first position; Y - strap 80 The operation of unit 1 will be described with reference to a pack 3 and the relative link 35a (35b) as of an initial instant, in which pack 3 is fed from feed conveyor 41 to chain 60 at station 21 of the trajectory B.

In this condition, the link 35a (35b) moves to the beginning of the section Pl and, therefore, the slot 40 is open. In addition, the casings 50 are arranged in the open position.

In detail, the gasket 3 is placed with the end flap 18 towards the plate 72 of the link 35, and slides on a wall 10a along the relative blade 43, so that the flap 18 is parallel to the blade 43 , until when the fin 18 enters the open slot 40.

In this condition, the package 3 is arranged above and, therefore, supported by the arm 145 of the body 142 carried by the link 35a (35b).

More precisely, the blade 43 cooperates with the wall 10a opposite the sealing band 4 of the package 3.

As the link 35a (35b) moves along the section Pl and a portion of section P2, the contrast surface 46 slidably cooperates with the end portion 8 of the package 3. In this way, the portions 8 and 9 they are coupled towards another, the flap 17 is bent over the flattened portion 8 and the flaps 20 are flexed relative to the portion 8 towards the axis A and on the opposite side of the portion 8, as shown in Figure 9.

In this condition, the fin 18 is housed with the site within the slot 40.

At the same time, each pair of consecutive links 35a, 35b moves towards each other along the section Pl. In this way, the angle between the consecutive links 35a, 35b decreases along the section Pl.

Accordingly, the lever 160 rotates about the portion 140 of the downstream link 35a, and the plate 162 moves toward the slot 40 of the upstream link 35a while the pins 161 slide into the relative slots 147 of the body 142 of the upstream link 35a.

At the end of the section Pl, the plate 72 of the link 35a is the first position in which the groove 40 engages.

As the plate 72 engages with the slot 40, the flap 18 is bent over the end portion 9. In particular, the flap 18 is bent on the opposite side of the sealing strip 4, ie, towards the wall 10a arranged upstream with reference to the direction of advance of the chain 60.

Simultaneously, fixed lifting elements 170 raise the flaps 20 towards the end portion 8 and the folded flaps 20 with respect to the axis A, as shown in FIGS.

Figures 8 and 9.

As the link 35b moves along the section P2, the housings 50 move from the open position to the fully closed position and the plate 72 is disposed in the first position.

Before the casings 50 reach the package 3, the nozzles 70, 71 direct air to the flaps 19, 20 of the package 3, to partially and locally melt the packing material of the flaps 19, 20 (Figure 9) and of the portion of the main portion 7 facing the flaps 19, 20.

Immediately thereafter, the casings 50 contact the walls 10b of packages 3 and press the flaps 20 on the relative upper ends of the walls 10b while the flaps 20 are cooled. In this condition, the housings 50 are arranged in the fully closed position.

Subsequently, the package 3 is disposed below the belt 80 and the projections 83 press the flaps 20 on the portion 9, while the flaps 20 are cooled.

In this condition, the volume of the folded gasket 2 is controlled by two blades 43 of the respective consecutive links 35a, 35b by the casings 50 arranged in the fully closed position, and by the projections 83 of the belt 80.

The folded pack 2 then pass along the Q portion of the path B.

Along the portion Q, the housings 50 move relative to one another from the fully closed position to the closed position, where they grab the packing 2, but substantially do not exert any type of pressure on it.

On the other hand, the housings 50 move together with the packing 2 in relation to the blade 43 parallel to the direction C, along the portion Q.

In this way, the housings 50, together with the folded packing 2 are staggered from the blade 43, at the end of the portion Q, so as to be releasable by the link 35 without interference with the blade 43 (Figure 10).

Further, along the portion Q and with the casings 50 in the fully closed position, the package 2 is coupled to a rotary device 100 shown in Figures 7, 10, 11, 12 and 13.

The device 100 is described in more detail in the European Application filed by the applicant with the number EP11187350.1.

Along the portion Q, each pair of consecutive links 35a, 35b move away from each other, as shown in Figure 1.

Therefore, the plate 72 of the current link 35b moves backward from the first to the second position, where it leaves the downstream link slot 40a free.

Finally, the folded pack 2 and the casings 50 arranged in the closed position are transported along the portion R.

It is important to mention that during the downward section of the portion Q and along the portion R of the path B, the folded gasket 2 is arranged below the plate 36 and is supported by the casings 50 arranged in the closed position.

In station 22, the housings 50 move back to the open position and the gasket 2 is released, under the action of gravity, to the output feed conveyor 42.

By being staggered relative to the casings 50 and the gasket 2, the blade 43 does not interfere with the release of the gasket 2.

Subsequently, the casings 50 are transported by the chain 60 to the station 21.

The advantages of unit 1 according to the present invention will be apparent from the above description.

In particular, the unit 1 bends the entire flap 18 of each package 3 in the end portion 9, by the downstream link movement plate 72a from the second position to the first position in which the groove 40 of the dock 40 engages. upstream link 35a.

In this way, the bending of the fin 18 is achieved by using a pair of elements, i.e., the slot 40 and the plate 72, which are both movable along the path B together with the respective upstream link 35a and downstream link 35b.

Accordingly, the flexure of the fin 18 is particularly accurate and highly repeatable, as compared to the known solution which is described in the introductory part of the present disclosure.

As a result, the overall quality of the bending is particularly high, as well as the overall final appearance of the packages 2.

In particular, the applicant has found that the flap 18 of each package 3 is bent over the end portion 9 much more coplanar than in the unit described in the introductory part of the present description.

Clearly, changes can be made to unit 1 without, however, departing from the scope of protection defined in the appended claims.

Unit 1 could comprise only one cam 61.

The unit 1 could form the package 2 having a polygonal or round cross section.

It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention.

Claims (12)

CLAIMS Having described the invention as above, the content of the following claims is claimed as property:

1. A folding unit for producing pourable food packages of sealed packages each having a main portion and opposite end portions disposed on opposite sides of the main portion; each package comprises, for each end portion, a flap and a pair of flaps projecting laterally from the main portion; The unit comprises: - a conveyor that is fed with a plurality of packages and that feeds the package along a formation path; Y - bending means interacting with each of the package along the formation path to bend the relative end flap over a relative end portion; the conveyor comprises at least one first link and one link articulated to each other; the second link is disposed downstream of the first link, with reference to a first forward direction of the conveyor along the forming path; characterized in that the bending means comprises: - a groove that is defined by the first link and is adapted to receive the end flap; Y a slider operatively connected to the second link and movable between a first position in which the slider at least partially engages the slot, in order to bend the final tab on a relative end portion and in a second, opposite direction to the first direction, and a second position in which the slide is separated from the slot.

2. The folding unit according to claim 1, characterized in that the slide is hinged to the second link.

3. The folding unit according to any of claims 1 or 2, characterized in that the slide comprises: - a plate adapted to interact with the end flap and bend it; Y - an integral arm with the plate and articulated to the second link.

4. The bending unit according to any of the preceding claims, characterized in that it comprises a body connected to the first link and defining the slot together with the first link.

5. The folding unit in accordance with claim 4, characterized in that the body defines a pair of recesses that are open on the opposite side of the first link and are adapted to receive the respective lateral portions of the vane.

6. The folding unit according to any of the preceding claims, characterized in that the slide comprises a pair of bolts and wherein the body defines a pair of slits disposed on the respective lateral sides of the slot and adapted to guide the bolts, when the slide moves between the first and second positions.

7. The bending unit according to claim 6, characterized in that the groove extends transversely to the path and the grooves extend tangentially to the path.

8. The bending unit according to claim 6, characterized in that each of the first link and the second link comprises a relative slot and a relative slider.

9. The bending unit according to any of the preceding claims, characterized in that each of the first link and second link comprises: - slot; Y - the slide that is arranged upstream of the slot, which proceeds according to the direction of travel of the first link and the second link along the training path.

10. The folding unit according to any of the preceding claims, characterized in that it comprises a fixed element that is adapted to lift, in use, the flaps towards the main portion.

11. The bending unit according to any of the preceding claims, characterized in that the formation path is a closed circuit path comprising: - a first curved portion along which the first and second link is fed, in use, with a relative pack for bending, and along which the first and second links advance towards each other; Y - a second rectilinear portion disposed downstream of the input portion along which the first and second link move substantially integrally to each other; the slide moves, in use, from the second position to the first position along the first curved part; the slide is disposed, in use, in the first position along the second rectilinear portion.

12. The folding unit according to claim 11, characterized in that the forming path also comprises a second curved portion. disposed downstream from the rectilinear portion proceeding along the advancing direction of the transport element, and along which the first and second links move, in use, away from each other; the slide moves, in use, from the first position to the second position, along the second curved portion. SUMMARY OF THE INVENTION A bending unit (1) is described for producing packages (2) of pourable sealed food products (3) each having a main portion (7) and opposite end portions (8, 9) disposed on opposite sides of each other. the main portion (7); each package (3) comprises, for each end portion (8, 9), a flap (17, 18) and a pair of flaps (19, 20) projecting laterally from the main portion (7); the unit (1) comprises: a conveyor (60) that is fed with a plurality of packages (3) and that feeds the package (3) along a formation path (B); and bending means (24) interacting with each package (3) along the forming path (B) to bend the relative end flap (18) onto a relative end portion (8); the conveyor (60) comprises at least one first and one second link (35a, 35b) hinged to one another; the second link (35b) is disposed downstream of the first link (35a), with reference to a first direction of advancement of the conveyor belt (60) along the formation path (B); the bending means (24) comprises: a groove (40) which is defined by the first link (35a) and is adapted to receive the end flap (18); and a slider (72) operatively connected to the second link (35b) and movable between a first position in which at least partially engages the groove (40), in order to bend the end flap (18) on a relative end portion (9), and a second position in which it is separated from the groove